Abstract

The magneto‐optic rotation has been investigated at 25 kbar using a diamond press and an electromagnet. The optical aperture does not impose intensity limitations. The sample area is 0.4 mm2 and its thickness about 20 μ. The Verdet constants of ferric polysaccharides were measured at a wavelength of about 0.65 μ. Raising the pressure to 25 kbar, the rotation decreases, in general, reversibly by about 65%. The piezo‐Verdet constant, defined as σ=(Vp−Vo)/Vop, is −27×10−6bar−1. This is the same relative change as that found for the magnetic susceptibility below 1 kbar.